To get the crossgrain straight, wash the fabrics first, then take them out of the dryer while still damp and iron them right away. I have a fairly long ironing board so I can lay the fabric the full width, I use my hand to straighten it out, then I do an up-and-down motion with the iron so that the selvage line is also straight.
You're probably saying 'Huh?' to this explanation.

No. I cut my sashings and borders to size first. If a portion of a block were the same size as a quilt top, it would be the same principle.

That is the way I've been doing it, and it seems to be working just fine. It's my first attempt at a log cabin and only my second time making a quilt. Thanks for all of the input. Glad to have suppport.
I only have the one ruler the longer one, do you think I should get the small and larger square one?

This is how I make mine too. The blocks move fast and easy and are very even. I have not ever had a failure.

Hey Gigigreen, this is an older thread and might not get the level of response you might want to get. I'm a believer in tools and the right tool for the job.

My recommendations is that everyone start with a 6.5 x 24" ruler, I don't like 6" rulers, want 6.5" so you can make 6" squares! That's your standard, it fits across the folded width of fabric, you can do amazing things with just this one ruler. Recently I've started using an older ruler with a textured bottom as my go-to, but I've used standard rulers for decades. Your ruler should have in addition to the inches and sub-units some of the common angles marked, at least one 45 degree marked, probably a 60 or others too.

I have a roll of 1/4" masking tape that is sold with the quilters supplies. I use it often to mark/reinforce lines on my rulers to help with my vision issues, really helps me be consistent!

After that, yes -- you will also want a smaller ruler. I suggest the second ruler be a large square, either 10.5 or 12.5" inches. If your log cabin blocks are going to finish to a standard ruler size, it might be a good excuse to get that one. And then you will want more smaller ones, either skinny and longer, or rectangles, or more squares. There are also acrylic cutting templates. I decided for my Fan quilt that I wanted that consistency of a nice hard fan blade and was happy to pay for that (most likely) one time use.

I have a long torso and short arms and I used to be heavier than I am now. I find I do my best cutting standing up and do all of my "long cuts" across the fabric standing. For me, dining room table height works, for my taller friends I suggest kitchen counter height. Sitting down I didn't have the reach and back then the tummy would push the ruler... I can do my smaller subcuts sitting but I've adapted to largely working standing anyway as a way to get a bit more activity out of my quilting. So stand when I pin, as well as cut.

That's a whole different topic but I've gone from being completely sedentary to getting my steps in each day without leaving my house by moving my various quilting stations throughout the house. Helps that it's just me and the hubby, and he works a lot and is very tolerant anyway. But I do my layout on our bed, sewing room is the small bedroom next to that, but the ironing board is set up in the living room and the cutting station is the dining room table.

I cut width of fabric, selvedge to selvedge.

Since I like and use paper-piecing to make my log cabins, I have found that it doesn't matter, LOF or WOF works. But I don't pre-cut, tried that once and had a mess. One of my cats decided to "help" sort the strips for me.

HouseDragon, please post a pix of your "Pink" log cabin quilt when finished. I also have a Granddaughter who loves pink. She turns Sweet Sixteen today.

Cutting log cabin
 

I cut my log cabin strips with an Accuquilt cutter. I cut on the length grain and never had any problems. If you cut on the cross grain making a wall hanging you will get some stretch. Pays to do it right the first time.

I found this topic interesting as I recently bought the Eleanor Burns Log Cabin book and plan to do a log cabin quilt as soon as I find fabric.